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Moderate Exercise Cuts Rate of Metabolic Syndrome

By Duke Medicine News and Communications

DURHAM, NC – Research from Duke University Medical Center shows
that even a modest amount of brisk walking weekly is enough to
trim waistlines and cut the risk of metabolic syndrome (MetS),
an increasingly frequent condition linked to obesity and a
sedentary lifestyle.

It's estimated that about a quarter of all U.S. adults have
MetS, a cluster of risk factors associated with greater
likelihood of developing heart disease, diabetes and stroke:
large waist circumference, high blood pressure, high levels of
triglycerides, low amounts of HDL, or "good" cholesterol, and
high blood sugar. To be diagnosed with MetS, patients must have
at least three of these five risk factors, and according to
many studies, a growing number of people do.

But Johanna Johnson, a clinical researcher at Duke Medical
Center and the lead author of a new study examining the impact
of exercise on MetS, said a person can lower risk of MetS by
walking just 30 minutes a day, six days per week. "That's about
11 miles per week. And our study shows that you'll benefit even
if you don't make any dietary changes."

"The results of our study underscore what we have known for
a long time," said Duke cardiologist William Kraus. "Some
exercise is better than none; more exercise is generally better
than less, and no exercise can be disastrous."

The study appears in the December 17 issue of the American
Journal of Cardiology.

The results come from a multi-year, federally funded study
called STRRIDE (Studies of a Targeted Risk Reduction
Intervention through Defined Exercise) that examined the
effects of varying amounts and intensity of exercise on 171
middle-aged, overweight men and women.

Before exercising regularly, 41 percent of the participants
met the criteria for MetS. At the end of the 8-month exercise
program, only 27 percent did.

"That's a significant decline in prevalence," said Johnson.
"It's also encouraging news for sedentary, middle-aged adults
who want to improve their health. It means they don't have to
go out running four or five days a week; they can get
significant health benefits by simply walking around the
neighborhood after dinner every night."

Still, some exercise regimens were better than others. Those
who exercised the least, walking about 11 miles per week,
gained significant benefit, while those who exercised the most,
jogging about 17 miles per week, gained slightly more benefit
in terms of lowered MetS scores.

One group puzzled the researchers, however. Those who did a
short period of very vigorous exercise didn't improve their
MetS scores as much as those who performed less intense
exercise a longer period.

Kraus, the senior author of the study, said there may be
more value in doing moderate intensity exercise every day
rather than more intense activity just a few days a week.

In all three of the study's exercise groups, waistlines got
smaller over the 8-month period. In general, men who exercised
saw greater improvement in their MetS risk factors than women.
But Johnson points out that at baseline, the men generally had
worse scores than women, "so they had more room to improve,"
she said.

Over the course of the STRRIDE study, the inactive control
group – those who didn't change their diet or activity level at
all – gained an average of about one pound and a half-inch
around the waist. "That may not sound like much, but that's
just six months," Kraus said. "Over a decade, that's an
additional 20 pounds and 10 inches at the beltline."

The study was funded by the National Institutes of
Health.

Colleagues at Duke who contributed to the study include Cris
Slentz, Gregory Samsa, Lori Bateman and Brian Duscha.
Collaborating authors from East Carolina University include
Joseph Houmard, Jennifer McCartney and Charles Tanner.